Gas burner

ABSTRACT

The present invention refers to a gas burner, in particular for domestic cooking appliances, comprising a bowl-shaped body ( 10 ) associated with a gas injector ( 11 ), a toothed crown ( 12 ) with a plurality of flame ports ( 13 ) placed over said body, and an upper cap ( 14 ) to close the burner top.  
     The burner is characterised in that a peripheral grove ( 15 ) is formed on at least a part of the external surface of the toothed crown ( 12 ), in order to increase the flame stability.

The present invention relates to a new gas burner, in particular for usein a domestic cooker, which is provided with an improved burner crown.

A gas burner is substantially formed by a bowl-shaped body, a toothedcrown and an upper cap. The bowl-shaped body is associated with aninjector through which the gas is supplied. The burner crown is providedon its circumference with a plurality of ports to let the gas-airmixture to go our in radial direction. The cap closes the burner top anddefines the flame ports together with the burner crown.

This kind of gas burner has flame ports equidistant each others of twoor more different sizes. Moreover, the flame ports could be differentalso in length and width, in order to let the gas-air mixture to leavethe burner at the desired velocity, pressure, inclination and at therequested distribution along the burner circumference.

Some burner ports have also the function of a pilot flame, and theyguarantee the flame stability when flow variations, for instance due tochanges of rate (maximum to minimum and viceversa), and external airturbulence could disturb the flame.

The flame stability under different operative conditions is a seriousproblem for all kind of gas burners.

A main drawback is the flame breakdown from the burner cap, which occursboth in longitudinal and in circular direction during the normalfunctioning of the burner.

At present, a technical solution to reduce this danger is represented bya cap whose diameter is larger than that of the burner crown, inparticular larger than the diameter of the flame port circumference.

This solution is not satisfactory from a technical point of view. Infact, the flame stability is also function of the burning velocity ofthe gas-air mixture. By increasing the quantity of air in the mixture,the quality of the combustion is improved, but also the burning velocityincreases; consequently, the flame stability decreases, approaching theflame lift limit. An enlarged diameter of the burner cap does not removesaid drawback.

In addition, a cap larger than the burner crown is not the bettersolution from the aesthetic point of view.

The main scope of the present invention is to provide a gas burner witha modified crown, which allows to overcome the above drawbacks, so asits functional and aesthetic characteristics are improved, without theneed to use a special and costly technology.

This and other scopes are obtained with a burner as claimed in theclaims of the present patent.

The invention will be better appreciated from the following descriptiongiven solely by way of non-limiting example and with reference to theaccompanying drawings, wherein:

FIG. 1 is an exploded view of a gas burner according to the presentinvention;

FIG. 2 is an enlarged perspective view of a part of a gas burneraccording to the present invention; and

FIG. 3 is an elevation side view of the gas burner of FIG. 2.

With reference to FIG. 1, a gas burner comprises: a bowl-shaped body 10,which is associated with a gas injector 11 to let the gas enter in theburner; a toothed crown 12, which leans on said bowl-shaped body 10 andis provided with a plurality of flame ports 13 circumferentiallyarranged along the periphery of the crown 12; and an upper cap 14, whichcloses the burner top.

Normally, the flame ports 13 are obtained by alternating high and lowteeth along the periphery of the crown 12

According to the present invention (FIGS. 2 and 3), a peripheral step 15is formed on at least a part of the external surface of the toothedcrown 12. The peripheral step 15 is preferably provided at a level lowerthan that of the flame ports 13 and its upper surface is smooth.Alternatively, at least part of the peripheral step 15 is crossed by anumber of radial grooves 16, which are connected with correspondingflame ports 13 of the toothed crown 12.

Shape and size of the peripheral step 15, in particular the ratiobetween width “x” and height “y” (FIG. 3), may be chosen depending onthe kind of gas to be used and on different functional parameters of theburner itself.

The peripheral step 15 gives to the burner ports an innovative doublesection shape, with the inner one (firstly met by the gas) having areduced section compared with the outer one. This feature creates a kindof “double conduit” which ensures a reduction for the flame velocity onthe external periphery of the toothed crown 12, so improving the flamestability and avoiding the danger of a flame detachment.

The peripheral step 15 allows also to obtain a better distribution ofthe flame around the toothed crown 12 and a faster cross-lighting of thegas-air mixture leaving the burner. Said advantages are achieved thanksto the continuity of the flame anchorage to the crown, which is ensuredby the step 15.

At last, by adopting the disclosed solution of the peripheral step 15,it is possible to employ an upper cap 14 having substantially the samediameter of the toothed crown 12, without any danger of flamedetachment. This feature further improves the functionality andaesthetic of the burner. Indeed, besides all the mentioned advantages,the burner according to the invention allows a reduction of volume ofthe flame under the pan support grids, so as to avoid the cooling of theflame that increases the CO production.

1. Gas burner, in particular for a domestic cooker, comprising abowl-shaped body (10) associated with a gas injector (11), a toothedcrown (12) with a plurality of flame ports (13) placed over said bodyand an upper cap (14) to close the burner top, characterised in that aperipheral step (15) is formed on at least a part of the externalsurface of the toothed crown (12).
 2. Gas burner according to claim 1,characterised in that said peripheral step (15) is formed at a levellower than that of the flame ports (13).
 3. Gas burner according toclaim 1, characterised in that said peripheral step (15) has a smoothsurface.
 4. Gas burner according to claim 1, characterised in that saidperipheral step (15) is at least partially crossed by radial grooves(16) connected with corresponding flame ports (13) of the toothed crown(12).
 5. Gas burner according to claim 1, characterised in that theupper cap (14) has substantially the same diameter of the toothed crown(12).
 6. Gas burner according to claim 2, characterised in that saidperipheral step (15) has a smooth surface.
 7. Gas burner according toclaim 2, characterised in that said peripheral step (15) is at leastpartially crossed by radial grooves (16) connected with correspondingflame ports (13) of the toothed crown (12).
 8. Gas burner according toclaim 2, characterised in that the upper cap (14) has substantially thesame diameter of the toothed crown (12).
 9. Gas burner according toclaim 3, characterised in that the upper cap (14) has substantially thesame diameter of the toothed crown (12).
 10. Gas burner according toclaim 4, characterised in that the upper cap (14) has substantially thesame diameter of the toothed crown (12).